Do painters love paint? As chefs love cream, according to a new show at the National Gallery. The analogy is pressed home - whips and whorls, glazes, creams and melting swipes - as if paint were a kind of ingredient. Which is a dumb, if literal, truth and scarcely in need of mention, yet it's taken so far that Passion for Paint might almost be the art version of a cooking demonstration: 100 ways with oil and watercolour.

The popular idea that painters must have a passion for paint is probably hard to budge, from Kirk Douglas smearing it ecstatically across the canvas as van Gogh to Colin Firth seductively fingering the moist paste in his mortar: Vermeer as a Dutch Mr Darcy.

Certainly, there have been passionate cooks. The artist who reputedly invented oil paint, Jan van Eyck, experimented with every imaginable oil before settling on fiendishly precise recipes of linseed and nut. Joshua Reynolds slaved over weird concoctions of egg, asphaltum, resin and pigment when aiming (but failing: the faces frequently fell from his portraits) for the look of 16th-century art.

But paint per se is not every artist's taste or obsession. Edward Hopper was entirely indifferent, he said, to the medium. Courbet wasn't alone in finding oil paint intolerably slow to dry and Monet, in old age, loathed the sticky practicalities.

Rothko's relationship with paint was deadly. He seems to have wanted to deny or transcend it. He thinned and thinned his buckets of pigment to the point where the celebrated murals created for Harvard University, finished in 1962, had all but vanished by 1979. Rothko once told a journalist that when the paint ran out, he just got some more at Woolworths, a bitter quip from an artist who believed his vision was let down by stuff.

Rothko would have been appalled by this show and I'm inclined that way, too. Vision is exactly what it ignores, along with individual style and paintings as anything much more than stuff pushed around a canvas. The idea, if you can crank it up so high, is that painters love doing different things with their medium. Van Dyke does virtuoso squiggles, Murillo does blurs, van Gogh goes for short, sharp strokes. Rembrandt's impasto is so thick, why he practically sculpts those faces.

Unarguable - and meaningless, too. So meaningless that practically anything done in Winsor & Newton could qualify for this show. Indeed, alongside a tremendous cast of stars - the flash of a Hals cavalier, a sublime Turner seascape, a Seurat sketch, a late Monet of water gliding so fast it appears motionless - are some absolute duds. Atrium artist Ian Davenport, whose work here looks like bad knock-off Bridget Riley, is included because he loves (or has made a lucrative career out of) putting daubs of paint on a canvas, upending it and letting those drips roll.

And the creepy dead-thing-under-a-stone art of Glenn Brown is included, not, one feels, because he has painted a meticulous reproduction of a photograph of a Frank Auerbach for philosophical reasons but because you can't see the brushwork. Incidentally, the curators are surely wrong to call Brown's work 'playful'. It would be hard to think of an artist more dispassionate, and less cheery, about paint.

The general method is compare and contrast, with an emphasis on the former. So Monet's expansive space is likened to the space in a violent purple landscape by Taiwanese artist Suling Wang. This looks like a graphic churned out by inkjet, although it was apparently made with rags and brushes on long poles. It gets its multiple perspective straight out of Japanese watercolours and computer games. Whereas the Monet is a meditation on the dissolution of space into light. The comparison is null and void.

It may be true that Gainsborough's quick and flickering brushwork in Mr and Mrs William Hallett is all about movement (it is aptly nicknamed 'The Morning Walk'). But the Murillo urchin nearby gets its movement from smooth blurring, not wildly abstract squiggles and scratches. Besides which, animation is the least interesting aspect of the Murillo compared to the fact that he was the first to paint a street child as a portrait.

This show can't quite decide what it wants to say about paint, never mind painting, in any case. It veers from telling you that the putty-coloured sky behind Veronese's dozing saint was blue until it faded to announcing that the paint in a David Bomberg landscape is correspondingly earthy, which it isn't.

It insists on the schoolbook version of Seurat as optical scientist 'interested in how different colours react against each other' (though which painter isn't?). Equally fatuously, the catalogue states that van Gogh's marvellous observation of 'sunlit colour on dark foliage can be seen as representing his mixed emotions'. Poor Vincent. Can he never get away from stupid cliches?

You might say that this is an innocent attempt to draw the public's attention to ways of painting and thus seeing. In fact, it is a jumble of ill-considered propaganda and shouldn't be excused, as books so often are, on the grounds that absolutely anything that gets people looking/reading must be a good thing.

My hope is that they will blink and shrug at the captions anyway. Take Degas's stupendous painting, La Coiffure. A woman leans back, clasping her head as if to protect it from the maid with her wrenching comb, the two of them connected by an electric current of red hair.

This mass of tresses is like some other living thing between them, suggesting just how bodily, and yet not quite human, is hair. The curators emphasise only the layering of hot colours and the fact that patches of canvas are bare, all of which goes without saying. What strikes is

the way this strange substance, which both women hold, hardly seems to belong to either but to the painting's dazzling red air.